The invention relates to an endless vehicular rubber track. The invention particularly relates to such track having a ground-contacting tread component of a rubber composition.
Endless rubber tractor tracks are increasingly being used for propelling various vehicles over the ground such as, for example, various tractors and other agricultural vehicles including, for example, combines and spreaders, as well as various earth moving machines.
In particular, such track is conventionally positioned over at least two wheels, normally a drive wheel for engaging an inner surface of the track and driving the track and at least one driven wheel to control the path of the track as it moves to propel the associated vehicle. The outer surface of the peripheral tread configuration of the track typically contains a plurality of raised lugs designed for engaging the ground and assisting the propelling of the associated vehicle such as, for example, a tractor over an agricultural ground, such as lugs, are referred to herein as ground-contacting lugs.
In practice, the ground-contacting tread of such rubber tracks provide a considerably wider footprint than conventional pneumatic tires and are, thereby, more adaptable to agricultural fields in that they offer better flotation and less soil compaction than rubber tires, which may result in better crop yield. In addition, use of rubber tracks instead of pneumatic tires may permit a farmer to get out into a field earlier in the planting season and plant crops sooner in point of time and may permit a harvesting of a crop on a more timely basis as compared to conventional pneumatic rubber tire equipped agricultural vehicles. Such use and advantages of rubber tractor tracks are well known to those having skill in such art.
Such rubber tracks are conventionally in a form of an endless rubber belt reinforced with continuous steel cables molded into the rubber composition itself to add dimensional stability for the track.
As the rubber track is driven around the aforesaid wheels, it is (1) subject to extensive contortional flexing and, thus, may be subject to tread crack initiation and propagation over time and (2) may be subject to various agricultural chemicals and crop stubble as is well known to those having skill in such art.
Accordingly, it is desired that the rubber composition for the ground-contacting tread component of the track have appropriate resistance to flex fatigue, resistance to abrasion and durability.
In the description of this invention, the term "phr" represents parts by weight of a particular material per 100 parts by weight of rubber. As used herein, the terms rubber and elastomer may be used interchangeably, unless otherwise identified.